Evaluation of different contour feather types for biomonitoring lead exposure in Northern goshawk (Accipiter gentilis) and tawny owl (Strix aluco)

The concentration of Pb was determined in feathers (contour feathers: mantle, pectoral, ventral, and primary- and secondary-coverts) of two sedentary species of raptors in Galicia (NW Spain): the tawny owl (Strix aluco) and the Northern goshawk (Accipiter gentilis). A high degree of intraindividual variability was observed in all types of feathers, with coefficients of variation exceeding 100 percent. The correlations between feather types were too low to enable use of a single type of body feather to predict the concentration of Pb in the other feathers. The number of body feathers required to differentiate individuals on the basis of the concentration of Pb was extremely high, in some cases higher than the number of the particular type of feather in the bird. All of this provides clear evidence that the contour and covert feathers of the raptor species considered cannot be used to biomonitor contamination by Pb, at least in this sample where the overall feather concentration were fairly uniform.